Extinction is a process of weakening the appropriate behavior of the person as he/she behaved previously.
Kathy's teacher didn't teach her not to behave like this and ultimately she increased her way of behaving towards the classmates which are called Extinction.
For example, if we are teaching our dog to shake hands with the people but after some time if we are not admiring him or else we are stopping to ask for the shake hand, we are weakening his way of conditioned behavior.
So finally Extinction stops us to make improvements in our unusual behavior.
